Question : My PC "freezes", no respons whatsoever.

Only remedy is restart to fail-safe mode via the on/off button, and then, when normal operation is resumed, It may freeze again within minutes. It is a Dell XPS M1330, with Vista and MSO 2007. A consultant have spent 2 hours (and 300 $), without result - searching for vira with no result.
I have gradually stripped it for all peripherals and the problem persists even with only a mouse connected. However the problem stopped when I disconnected the Wireless Network (WLAN) - by switching off the Wi-Fi catcher - and used a broadband modem cable instead. This takes place at my office - at home (and other places, like hotels etc) I have no problems using WLAN.

So my problems may be solved - at least the symptoms have gone, but I should very much like to know if anyone have experienced similar problems, and what you have done about it. In principle there may still be a hardware/software problem somewhere in the network system, or one of the wireless network close to my office may send "dirty" signals which causes my PC to freeze.

So if anyone have experienced similar problems, I should very much like to know. Thanks in advance.

Answer : My PC "freezes", no respons whatsoever.

By mistake I have had Wifi running as well as my mobile broadband adapter - and that makes Vista choose one of them only. As both of them are heading toward the Internet the problem is only the speed. If you are comfortable with IP addressing, the command route print under the command prompt would give you some information on what is actually going on from your computer in different situations. The rightmost column would give you the relative speed of different channels.

However, as you have admitted, you switch off the wifi in your office - that would of course be the only straightforward thing to do in your situation. If you use wifi you should use one preferred SSID/pass phrase combination only and for security never use any open wifi networks ever.